1. Field of the Invention
The present invention relates to a plate-making apparatus and a printing plate manufacturing method, and more particularly, to a multi-beam exposure technique suitable for manufacturing a printing plate such as a flexographic plate and a printing plate manufacturing technique applying this.
2. Description of the Related Art
Conventionally, there has been known a plate-making apparatus using a plate material such as a flexo, which rotates a drum in a main scanning direction, on an outer peripheral surface of which the plate material is mounted as well as scans laser beams in a sub-scanning direction according to image data to perform laser engraving on the plate material. The laser engraving is a plate-making method having high degree of freedom for a three-dimensional shape in that an arbitrary three-dimensional shape can be set using parameters such as the size, depth, inclination, and inclined expansion of a top portion for each pixel. In general, when a flexographic material is engraved, the engraved shape is often specified. For example, the size of the top portion is determined by the document (image data), but it is difficult to obtain the depth, inclination, and inclined expansion thereof simply from the document. Therefore, the user often adjusts the depth, inclination, and inclined expansion thereof according to the type and the hardness of the plate material (paper, heavy paper, film, etc.) and the type of the document (line drawing, natural image, etc.).
Japanese Patent Application Laid-Open No. 2006-239702 discloses a laser machining apparatus using a plurality of laser emission units. In order to prevent variations occurring in a machined state due to individual differences in each laser emission unit and the like, calibration information for correcting laser intensity deviation to a workpiece is stored. The calibration information is used to correct a command signal used to control the emission intensity of each laser emission unit.